stdio_stream_write() specifications

Signature

static size_t stdio_stream_write(
    void *backend,
    const void *buf,
    size_t n,
    stream_status_t *st);

Purpose

Write up to n bytes from buf to the output-oriented standard stream wrapped by the stdio_stream backend.

Preconditions

• If backend != NULL, backend must point to a valid stdio_stream_t.
• If n > 0, buf must designate at least n readable bytes.

Invalid arguments

• backend must not be NULL.
• If n > 0, buf must not be NULL.

Success

• Returns the number of bytes written to the wrapped standard stream.
• If st != NULL, stores STREAM_STATUS_OK in *st.
• If n == 0, returns 0 and, if st != NULL, stores STREAM_STATUS_OK in *st.

Failure

• Returns 0 and, if st != NULL, stores STREAM_STATUS_INVALID for invalid arguments.
• Returns 0 and, if st != NULL, stores STREAM_STATUS_IO_ERROR when the wrapped standard stream does not support writing.

Notes

• This function is an internal backend callback used by the borrower-side stream_write() operation.
• The write is forwarded through the injected osal_stdio_ops_t::write callback bound in the backend handle.
• The returned value is expressed in bytes.
• This function does not take ownership of backend or buf.
• Writing is supported only for output-oriented standard streams:
  • stdout
  • stderr
• Writing to stdin is rejected by contract.